1. Technical Field
The present invention relates to a source driving device and, in particular, to a source driving device with automatic de-skew capability.
2. Description of Related Arts
Due to rapid developments in technology, the LCD is now applied in a wide range of electronic devices such as mobile phones, PCs, laptops, and flat-screen TVs. A timing controller of a LCD is usually utilized for generating data signals, related to imaging displays, control signals and clock signals for driving the LCD panel. The source driving device of the LCD executes logic calculations based on data signals, clock signals and control signals to generate driving signals for the LCD panel.
The transmission interfaces, including TTL (Transistor-Transistor Logic), LVDS (Low-Voltage Differential Signaling), RSDS (Reduced Swing Differential Signaling) and mini-LVDS (Mini Low-Voltage Differential Signaling), are widely applied on the current LCD. However, it is necessary for data signals, control signals and clock signals to work together in harmony whether transmitting signals via any of interfaces, so that the internal logic circuit of the source driving device may correctly read data for generating correct driving signals.
Resulting from the development of large scale LCDs, users have a high demand for resolution quality and as such, the size of the LCD panel, quantity of the source driving devices and size of the data transmitting interfaces are also increased, such as PCBs. Therefore, signal transmitting paths between the timing controller and the source driving device of large scale LCDs become longer, so that the signal transmitting time also becomes longer. Moreover, since the circuit layouts between the timing controller and different source driving devices are different from each other, the distance of the signal transmitting paths between the timing controller and different source driving devices are also different. Due to every driving device having a different toggle rate, ground shielding and driving capability during the output stage, different source driving devices may receive signals with different delays. Consequently, the phase difference of is the signals may deviate from a predetermined deviation so that the internal circuit of the source driving device cannot correctly read data. The signal skew may greatly affect the display quality of the LCD, especially in high frequency applications.
In conventional LCDs, the phase relationship between data signals and clock signals, generated by the timing controller, are fixed. The set-up time and hold time are also fixed. Due to different source driving devices include differences in the distance of signal transmitting paths, toggle rates, ground shielding and driving capability during the output stage, the data signals and clock signals, with different delays, are received by the source driving device. As a result, the conventional LCD may lack the ability to automatically de-skew, such that the LCD may have an inferior display quality.
Therefore, the present invention provides a device with an automatic de-skew capability.